1. Field of the Invention
The present invention relates generally to sliding-vane rotary compressors for compressing gaseous or liquid compressible mediums, and more particularly to a sliding-vane rotary compressor for use in an automobile air conditioner for compressing a refrigerant carrier.
2. Prior Art
Sliding-vane rotary compressors of this type include a circular rotor rotatably received in an elliptical bore in a cylinder and carrying thereon a plurality of radially movable vanes held in sliding contact with the inner peripheral surface of the cylinder. The rotor is fixedly mounted on a drive shaft rotatably supported by a pair of bearings mounted, respectively, in a front side block and a rear side block. Since the bearings need lubricating, a refrigerant carrier entraining a lubricating oil must be supplied to the bearings. The refrigerant carrier supplied to the bearings is prevented by a shaft seal from leaking to the outside of the compressor along the drive shaft. The shaft seal also needs to be lubricated.
The bearings and the shaft seal are lubricated by a portion of the aforesaid lubricating oil-entraining refrigerant carrier which is introduced from a low pressure chamber in consideration of the cooling efficiency and the sealing properties. Since the low pressure chamber is normally disposed on a front-side-block side of the compressor, the bearing and the shaft seal disposed on this side are directly lublicated by the refrigerant carrier supplied from the low pressure chamber at a low pressure. The low pressure chamber is however not always disposed on the front-side-block side but sometimes disposed on the opposite side, i.e. the rear-side-block side so as to conform to a mode of application of the compressor.
In such compressor having a low pressure chamber on its rear-side-block side, a guide hole is formed longitudinally in a rotor drive shaft to intercommunicate the low pressure chamber on the rear-side-block side and a bearing and a shaft seal disposed on a front-side-block side, thereby supplying the refrigerant carrier to the bearing on the front-side-block side.
The compressor having such guide hole is still disadvantageous in that since the bearing and the shaft seal on the front-side-block side are held in air tight, a pressure difference produced in the guide hole is insufficient to cause the refrigerant carrier to flow through the gudie hole to the bearing and the shaft seal, thereby lubricating the latter.
With this insufficient lubricating, the bearing is likely to cause a seizing or undue abrasive wear due to commulative frictional heat.